Vertical distribution of fungi in hollows and hummocks of boreal peatlands

- Fungal communities are more diverse in hollows than hummocks of boreal peatlands.
- Both hollows and hummocks have an area of maximum fungal diversity.
- The area of high fungal diversity is most likely driven by peat moisture.

Hollows and hummocks of boreal peatlands differ in water table position, pH, plant community composition and biochemical properties that might affect the structure of their fungal communities. The community composition of fungi at three depths (0-5 cm, 15-20 cm, 30-35 cm) in hollows and hummocks of a nutrient-poor fen in northern Ontario, Canada were assessed by Illumina sequencing of 28S amplicons. Our metabarcoding results revealed statistically distinct fungal community composition between hollows and hummocks. Hollows contained a more diverse fungal community than hummocks. However, the middle horizon of hollows and the bottom horizon of hummocks were comparable in terms of fungal biodiversity. These layers were identified as the areas bearing the most diverse community composition of fungi, most likely driven by their similarly respective distance from the water table position. This optimum area is expected to be most affected following water table drawdown under future climate change conditions.